Rockwell Automation 1557 MEDIUM VOLTAGE AC DRIVE - Manual (Page 275)

TROUBLESHOOTING 10-33
1557-UM050F-EN-P – June 2013
Meggering Procedure
The following procedure is to be used during commissioning or troubleshooting. Meggering the drive
allows you to find any ground faults without damaging the drive.
1. Disconnect any incoming power sources, medium voltage sources should be locked off and control
power should be turned off at the circuit breaker.
2. Verify with potential indicator that power has been disconnected.
3. Disconnect the following:

The J1, J2 Ribbon cables and Gnd. Wires on all Voltage Feedback Boards (VFB).

The Gnd. Wire connection at the Output Ground Network.
4. Connect the megger between cabinet ground and one of the drive input or drive output terminals and
megger the drive with a DC voltage equivalent to its AC rating. The reading should be 5,000 Meg
Ohms at least, preferred is 10,000 Meg Ohms plus for one minute. The reading will vary depending
upon the size and number of output capacitors. If in doubt isolate the output capacitors
5. Discharge the system to ground.
6. Reconnect the ribbon cables and gnd wires that were previously disconnected.
If you obtain values below the recommended, contact Medium Voltage Product Support.